On National DNA Day, officials in Sacramento arrested Joseph James DeAngelo, 72, the prime suspect for the case of the Golden State Killer. Genealogy sites that use DNA sampling led to narrowing the field of suspects and gave new life to this decades-old cold case.

Neighbors noted that DeAngelo was a “strange” or “odd” person. He mostly kept to himself, but people never suspected him of committing the series of rapes and murders attributed to the Golden State Killer. DeAngelo was a cop for 6 years with the Auburn Police Department in California and was fired from the force for allegedly shoplifting at a local drugstore. It is believed that DeAngelo made use of his previous cop experience to effectively hide the murders and assaults.

The 40-year investigation came to a close due in large part to DeAngelo’s DNA samples left behind at crime scenes. With the advent of tracing families through websites that use DNA, police were able to upload DNA from the crime scenes and match that DNA to a relative who shared DNA as a part of tracing family lineage. It was a long shot for the cold case detectives that paid off. Police then surveilled DeAngelo’s home for viable DNA samples like gum, a drinking straw, or cigarette butt. 6 days into the surveillance, the right trash with DNA was retrieved. Currently, DeAngelo is facing capital murder charges in multiple counties of California.